Evolutionary traces of miniaturization in a giant—Comparative anatomy of brain and brain nerves in Bathochordaeus stygius (Tunicata, Appendicularia),Journal of Morphology

当前位置： X-MOL 学术 › J. Morphol. › 论文详情

Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)

Evolutionary traces of miniaturization in a giant—Comparative anatomy of brain and brain nerves in Bathochordaeus stygius (Tunicata, Appendicularia)
Journal of Morphology ( IF 1.5 ) Pub Date : 2023-05-18 , DOI: 10.1002/jmor.21598
Berit Zemann ₁ , Mai-Lee Van Le ₂ , Rob E Sherlock ₃ , Daniel Baum ₄ , Kakani Katija ₃ , Thomas Stach ₂

Affiliation

Appendicularia comprises 70 marine, invertebrate, chordate species. Appendicularians play important ecological and evolutionary roles, yet their morphological disparity remains understudied. Most appendicularians are small, develop rapidly, and with a stereotyped cell lineage, leading to the hypothesis that Appendicularia derived progenetically from an ascidian-like ancestor. Here, we describe the detailed anatomy of the central nervous system of Bathochordaeus stygius, a giant appendicularian from the mesopelagic. We show that the brain consists of a forebrain with on average smaller and more uniform cells and a hindbrain, in which cell shapes and sizes vary to a greater extent. Cell count for the brain was 102. We demonstrate the presence of three paired brain nerves. Brain nerve 1 traces into the epidermis of the upper lip region and consists of several fibers with some supportive bulb cells in its course. Brain nerve 2 innervates oral sensory organs and brain nerve 3 innervates the ciliary ring of the gill slits and lateral epidermis. Brain nerve 3 is asymmetric, with the right nerve consisting of two neurites originating posterior to the left one that contains three neurites. Similarities and differences to the anatomy of the brain of the model species Oikopleura dioica are discussed. We interpret the small number of cells in the brain of B. stygius as an evolutionary trace of miniaturization and conclude that giant appendicularians evolved from a small, progenetic ancestor that secondarily increased in size within Appendicularia.

中文翻译：

巨人小型化的进化痕迹——Bathochordaeus stygius（被囊，附肢）大脑和脑神经的比较解剖学

附肢动物包括 70 种海洋、无脊椎动物、脊索动物物种。附肢动物发挥着重要的生态和进化作用，但它们的形态差异仍未得到充分研究。大多数阑尾动物体型较小，发育迅速，并且具有固定的细胞谱系，这导致了一种假说：阑尾动物是从类似海鞘的祖先衍生而来的。在这里，我们描述了Bathochordaeus stygius中枢神经系统的详细解剖结构，来自中层的巨型阑尾动物。我们证明大脑由前脑和后脑组成，前脑的细胞平均更小、更均匀，后脑的细胞形状和大小变化更大。大脑的细胞计数为 102。我们证明了三对脑神经的存在。脑神经 1 延伸至上唇区域的表皮，由多条纤维组成，其走行中带有一些支持性球细胞。脑神经 2 支配口腔感觉器官，脑神经 3 支配鳃缝睫状环和外侧表皮。脑神经 3 是不对称的，右侧神经由两个神经突组成，其起源于左侧神经突，左侧神经突包含三个神经突。与模式物种Oikopleura dioica大脑解剖结构的异同进行了讨论。我们将B. stygius大脑中的少量细胞解释为小型化的进化痕迹，并得出结论，巨型阑尾动物是从一个小的后代祖先进化而来的，该祖先在阑尾内的尺寸随后增加。

更新日期：2023-05-22

点击分享查看原文

点击收藏

公开下载

阅读更多本刊新发论文本刊介绍/投稿指南